In a typical diesel engine arrangement, a reservoir or tank is provided with diesel fuel that supplied to the diesel engine. A recirculating diesel fuel circuit extends between the engine and the fuel tank in which one fuel line extends from the fuel tank to the diesel engine to supply the engine with fuel, and another fuel line extends from the diesel engine back to the fuel tank to return overflow fuel to the tank.
Due to the great heat generated by the engine, a fuel cooler is usually provided to cool the fuel. Without a fuel cooler the diesel fuel may get so hot that it damages the injector pump or other components or causes the engine (through other controls) to “derate” or reduce its power output.
The fuel cooler is typically disposed to cool the overflow fuel that flows back from the engine to the fuel tank.
In US 2003/005913 A1, an arrangement for switching the location of a fuel cooler in a fuel supply circuit is shown. The fuel cooler is switched from cooling fuel exiting the internal combustion engine, to being removed from the fuel supply circuit entirely. This arrangement does not disclose a fuel cooler use to cool fuel flowing from a fuel tank to an engine. Furthermore, it does not disclose a cooler disposed between the engine and the fuel tank to cooled fuel exiting the engine and returning to the fuel tank.
In U.S. Pat. No. 6,457,460 B1, a cooler is provided to cool pressurized fuel as it travels in the opposite direction: from the fuel tank to the engine. The function is to extract heat from the fuel and thereby prevent the fuel from vaporizing.
In U.S. Pat. No. 6,234,151, two fuel coolers (19, 21) are shown disposed between the injectors and the fuel tank. One (21) is switched into the circuit to provide cooling when pressure at a valve (17) exceeds a predetermined value.
This may be inadequate in some arrangements, particularly when the fuel tank itself is in a hot environment and can absorb heat energy. In these cases, the fuel in the fuel tank may pick up enough heat after arriving in the tank that by the time the fuel returns to the engine it is too hot and cause engine damage, or derating (i.e. an automatic reduction in power) of the engine.
In a situation like this, it would be beneficial to have a fuel cooler disposed between the fuel tank and the engine. However, when the engine is cold, and the fuel is already below a preferred temperature, cooling the fuel from the fuel tank before it arrives at the engine may cause the fuel to get too cold and “gel”.
Thus, if the fuel is hot, it may be beneficial to cool the fuel as it travels from the fuel tank to the engine. If the fuel is cold, it may be beneficial to cool the fuel as it travels from the engine to the fuel tank.
It would be beneficial to have a diesel fuel supply circuit that can alternatively position the fuel cooler between the engine and the fuel tank to cool the fuel in its return path to the tank, and to alternatively position the fuel cooler between the fuel tank and the engine to cool the fuel on its way from the fuel tank to the engine.
These benefits are provided by the arrangement described in claim 1. Further benefits are provided by the alternative arrangements described in the additional claims.